1. Field of the Invention
The present invention relates generally to the field of mine detection apparatus which can detect metal and non-metal buried mines by recognizing passive microwave radiation signatures thereof.
2. Prior Art
The number of buried mines that continue to present a threat of severe injury and death well after their intended effective period of use, is staggering. There are over one-hundred million buried mines, many of which were specifically designed to be difficult to detect. New types are made of plastic or other non-metal materials which make their detection more problematic. Moreover, the use of buried mines during battle, from minor skirmishes to all out war, present a major threat to military and civilian personnel. Accordingly, there is an ongoing need for mine detection systems which are effective in locating metal and non-metal buried mines, which are sufficiently low cost and portable to be provided in large numbers, which are conducive to use by individual military personnel as well as on robotic and vehicular platforms and which can be operated without any requiring large power sources or exotic electronic devices.
The following list of U.S. patents were found but are not considered pertinent. The patents are now listed:
U.S. Pat. No. 3,028,596 McGillem et al PA1 U.S. Pat. No. 3,129,330 Seling PA1 U.S. Pat. No. 3,230,532 Whitney PA1 U.S. Pat. No. 3,599,207 Foiani et al PA1 U.S. Pat. No. 3,599,211 Mardon PA1 U.S. Pat. No. 3,982,125 Roder PA1 U.S. Pat. No. 4,115,776 Roeder et al PA1 U.S. Pat. No. 4,521,861 Logan et al PA1 U.S. Pat. No. 4,641,566 Pomeroy PA1 U.S. Pat. No. 4,775,853 Perez Borruate PA1 U.S. Pat. No. 4,872,014 Nowogrodzki PA1 U.S. Pat. No. 5,012,099 Paturel et al PA1 U.S. Pat. No. 5,121,124 Spivey et al PA1 U.S. Pat. No. 5,160,934 Alpers et al PA1 U.S. Pat. No. 5,214,281 Rowe PA1 U.S. Pat. No. 5,218,345 Muller et al PA1 U.S. Pat. No. 5,227,800 Huguenin et al PA1 U.S. Pat. No. 5,266,799 Steinitz et al PA1 U.S. Pat. No. 5,286,973 Westrom et al PA1 U.S. Pat. No. 5,311,273 Tank et al PA1 U.S. Pat. No. 5,324,948 Dudar et al PA1 U.S. Pat. No. 5,354,987 MacPherson PA1 U.S. Pat. No. 5,365,237 Johnson et al PA1 U.S. Pat. No. 5,371,358 Chang et al PA1 U.S. Pat. No. 5,381,422 Brown et al PA1 U.S. Pat. No. 5,412,206 Seidel et al PA1 U.S. Pat. No. 5,438,336 Lee et al PA1 U.S. Pat. No. 5,445,453 Prelat PA1 U.S. Pat. No. 5,461,229 Sauter et al PA1 U.S. Pat. No. 5,471,056 Prelat PA1 U.S. Pat. No. 5,483,339 Van Aken et al PA1 U.S. Pat. No. 5,495,106 Mastny PA1 U.S. Pat. No. 5,506,406 Kapp et al PA1 U.S. Pat. No. 5,548,115 Ballard et al PA1 U.S. Pat. No. 5,559,332 Meissner et al PA1 U.S. Pat. No. 5,561,294 Iddan PA1 U.S. Pat. No. 5,585,628 Andrews et al PA1 U.S. Pat. No. 5,585,632 Hull et al PA1 U.S. Pat. No. 5,587,583 Chin et al PA1 U.S. Pat. No. 5,600,139 Mladjan et al PA1 AP Anti-personnel PA1 ELINT Electronic Intelligence PA1 EMI Electromagnetic Interference PA1 FAR False-Alarm Rate PA1 GPR Ground Penetrating Radar PA1 HM High Metal PA1 IC Induction Coil PA1 IIR Imaging Infrared PA1 LM Low Metal PA1 LNA Low-Noise Amplifier PA1 NM Non-metal PA1 P.sub.d Probability of Detection PA1 P.sub.FA Probability of False Alarm PA1 RFBW Radiometer Frequency BandWidth PA1 RFI Radio Frequency Interference PA1 RIS Radiometric Interference Signature PA1 SCR Signal-to-Clutter Ratio PA1 SNR Signal-to-Noise Ratio
U.S. Pat. No. 5,227,800 to Huguenin et al is directed to a millimeter wave detection system that provides an image to a video display of contraband including plastic and ceramic concealed weapons. The system can be passive as shown in the radiometric embodiment, FIG. 6, or can use amplitude modulated source arrays of linearly polarized radiation to illuminate the field of view. A pair of arrays 162, 164 of gun diodes emit quasi-coherent radiation which is linearly polarized for improved detection. A camera 166 having antenna detector array 36 made of elements 66, each a balanced antenna with diode provides a signal representing the image of the field of view. One of the several embodiments has provisions for varying the polarization so as to enhance the detection of both metallic and non-metallic targets.
U.S. Pat. No. 4,641,566 to Pomeroy is directed to a method for detecting plastic mines that have been buried for a long time, so that the temperature differences vanish and thermal detectors no longer function effectively. A solution 22 of a detachable material is sprayed uniformly over a surface are by helicopter or airplane. The solution percolates downward through the earth and coats the upper surface 26 of mine 10. The recognizable shape 40 of the mine can be detected by detector 52 and displayed on screen 62.
U.S. Pat. Nos. 5,445,453 and 5,471,056 both to Prelat are directed to a method of airborne surveying that includes determining the thermal inertia of the earth's surface, particularly useful in exploration for natural resources, environmental assessment, as well as ground target identification. A sensor processing unit 12 containing spectrometer assemblies 14, 16, 18 each configured to receive a radiometric band of frequencies are mounted on an airborne platform. A central processor 24 converts image data into radiometric units to perform atmospheric correction and geometric rectification to enhance the received data. Post flight processing of a first airborne mission under conditions of lowest solar heating and a second airborne mission of maximum solar heating can determine the thermal inertia of the ground.
U.S. Pat. No. 5,371,358 to Chang et al is directed to an imaging spectrometer adapted to low altitude, low speed, airborne applications for geophysical, geological, and environmental surveys. Radiant energy at various wavelengths is reflected from terrain 10 and is received by an imaging system located in aircraft 12. The imaging system has a plurality of spectrometers 24, 26, 28, 30, the spectrometer being equipped with a bandpass filter and a plurality of detecting elements, provides up to 128 corresponding channels with a variable bandwidth optimized to provide the highest practical signal-to-noise ratio for each desired wavelength. The system is under the control of a system controller and data acquisition unit 120 and interfaces with the spectrometers and detectors, scanners, gyroscope 132, data recorder, storage unit, onboard monitoring display, hard copy recorder, and ground data processing computer.
U.S. Pat. No. 5,365,237 to Johnson et al is directed to a camera system that is capable of imaging objects through media such as wood, or fog, providing a greater field of view and a simpler system. The camera system modulates an optical beam with the signal received from the antenna to impose the spectral components that are a function of the received frequencies of the microwave radiation. The signal received from antenna 6 is used to modulate an optical beam from laser 12. The modulated beam is processed through the rest of the system including the etalon 35 and finally supplied to a video camera 8. The one-dimensional image could be converted to a two-dimensional image by panning the camera system, mounting the camera on a moving platform, or providing an array of antennas and a corresponding number of optical modulators. The image from the video camera can be supplied to video monitor 58.